static void do_signal()

in kernel/signal.c [849:918]

• 40 lines of code
• 16 McCabe index (conditional complexity)

static void do_signal(struct pt_regs *regs)
{
	unsigned long continue_addr = 0, restart_addr = 0;
	int retval = 0;
	struct ksignal ksig;
	bool syscall = in_syscall(regs);

	/*
	 * If we were from a system call, check for system call restarting...
	 */
	if (syscall) {
		continue_addr = regs->pc;
		restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
		retval = regs->regs[0];

		/*
		 * Avoid additional syscall restarting via ret_to_user.
		 */
		forget_syscall(regs);

		/*
		 * Prepare for system call restart. We do this here so that a
		 * debugger will see the already changed PC.
		 */
		switch (retval) {
		case -ERESTARTNOHAND:
		case -ERESTARTSYS:
		case -ERESTARTNOINTR:
		case -ERESTART_RESTARTBLOCK:
			regs->regs[0] = regs->orig_x0;
			regs->pc = restart_addr;
			break;
		}
	}

	/*
	 * Get the signal to deliver. When running under ptrace, at this point
	 * the debugger may change all of our registers.
	 */
	if (get_signal(&ksig)) {
		/*
		 * Depending on the signal settings, we may need to revert the
		 * decision to restart the system call, but skip this if a
		 * debugger has chosen to restart at a different PC.
		 */
		if (regs->pc == restart_addr &&
		    (retval == -ERESTARTNOHAND ||
		     retval == -ERESTART_RESTARTBLOCK ||
		     (retval == -ERESTARTSYS &&
		      !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
			syscall_set_return_value(current, regs, -EINTR, 0);
			regs->pc = continue_addr;
		}

		handle_signal(&ksig, regs);
		return;
	}

	/*
	 * Handle restarting a different system call. As above, if a debugger
	 * has chosen to restart at a different PC, ignore the restart.
	 */
	if (syscall && regs->pc == restart_addr) {
		if (retval == -ERESTART_RESTARTBLOCK)
			setup_restart_syscall(regs);
		user_rewind_single_step(current);
	}

	restore_saved_sigmask();
}